title: Spooky sodium balance.
abstract: Current teaching states that when sodium intake is increased from low to high levels, total-body sodium (TBNa) and water increase until daily sodium excretion again equals intake. When sodium intake is reduced, sodium excretion briefly exceeds intake until the excess TBNa and water are eliminated, at which point sodium excretion again equals intake. However, careful balance studies oftentimes conflict with this view and long-term studies suggest that TBNa fluctuates independent of intake or body weight. We recently performed the opposite experiment in that we fixed sodium intake for several weeks at three levels of sodium intake and collected all urine made. We found weekly (circaseptan) patterns in sodium excretion that were inversely related to aldosterone and directly to cortisol. TBNa was not dependent on sodium intake but instead exhibited far longer (≥ monthly) infradian rhythms independent of extracellular water, body weight, or blood pressure. The findings are consistent with our ideas on tissue sodium storage and its regulation that we developed on the basis of animal research. We are implementing (23)Na-magnetic resonance imaging (MRI) to pursue open questions on sodium balance in patients. Our findings could be relevant to therapeutic strategies for hypertension and target-organ damage.
authors.affiliation: 1] Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany [2] Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
authors.forename: Jens
authors.initials: J
authors.lastname: Titze
authors.affiliation: Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Dahlmann
authors.affiliation: Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Lerchl
authors.affiliation: Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kopp
authors.affiliation: 1] Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany [2] Experimental and Clinical Research Center, an institutional cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Rakova
authors.affiliation: Interdisciplinary Center for Clinical Research and Department for Nephrology and Hypertension, Nikolaus-Fiebiger Center for Molecular Medicine, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Schröder
authors.affiliation: 1] Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA [2] Experimental and Clinical Research Center, an institutional cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Friedrich C
authors.initials: FC
authors.lastname: Luft
mesh_terms: D000818:Animals; D006801:Humans; D012964:Sodium / Q000008:administration & dosage / Q000652:urine*; D014882:Water-Electrolyte Balance
chemical_list: D012964:Sodium